Thermostats have been used for many years as temperature sensitive switches which control heating and/or cooling equipment for conditioning a space in which the thermostat, or a temperature sensor connected to the thermostat, is placed. In the well known manner, a simple thermostat can be adjusted to establish a temperature set point such that, when the temperature in the conditioned space reaches the set point, the thermostat interacts with the heating and/or/cooling equipment to take suitable action to heat or cool the conditioned space as may be appropriate for the season as established by a user.
Modern thermostat systems, which take advantage of the ongoing rapid advances in electronic technology and circuit integration, have many features which provide more precise supervision of the heating and/or cooling equipment to achieve more economical and more comfortable management of the temperature of a conditioned space. Many modern thermostat systems include a real time clock, a memory and a data processor to run a process control program stored in the memory; Such thermostats accurately measure the temperature of a temperature sensor disposed in the conditioned space and make decisions to send control signals to the heating and/or cooling equipment in order to closely control the temperature of the conditioned space. The use of programmed thermostat systems permits anticipating and minimizing hysterisis or overshoot of the temperature in the conditioned space. In addition, the program can specify different set points at different times of the day and week and may also include a “vacation” mode which employs different set points when the conditioned space is not occupied for an extended period.
Many modern thermostat systems are programmable by a user. Typically, prior art programmable thermostat systems employ a set of fixed position, button-actuated switches to be depressed in a precise sequence to program set points (which may vary with the day of the week) for programmable time periods which may include a vacation mode. The programming sequence may be followed on a separate display, typically an LCD with segmented text characters. In some modern thermostats, “virtual” buttons are presented on the LCD itself which is juxtaposed with a touch pad to effect an interactive touch screen.
There is a fundamental problem with the prior art programmable thermostat systems: they are difficult to program to the extent that some users are unable to successfully program them. This is because the user interfaces which have been employed in prior art programmable interfaces are not highly intuitive. Programmable thermostat systems have incorporated fixed position real or virtual buttons, at least some of which have multi-functions depending upon the point which a user has reached in the programming process. The user must usually refer to and attempt to decipher a programming manual (which is often difficult for the average user to readily understand) as the programming proceeds. But, the programming process is so complex to follow while trying to remember the instructions that many users give up, and the full capabilities of the thermostat system cannot be utilized.
Outside of the art of programmable thermostat systems and programmable thermostats, dot matrix LCDs, which have pixel display elements arranged in rows and columns, are widely used. Dot matrix LCDs are not common as user-visible displays on programmable thermostats for viewing alphanumeric and iconic graphic information although such a thermostat is disclosed in, and particular features claimed in, co-pending U.S. patent application Ser. No. 10/440,474, filed May 15, 2003, and entitled: “Reverse Images in a Dot Matrix LCD for an Environmental Control Device” by Howard B. Rosen, incorporated by reference herein.
This limited use of dot matrix LCDs in programmable thermostats is because of basic engineering and practical considerations. Displayed information for a programmable thermostat generally includes such things as environmental conditions, heating and/or cooling equipment operation or non-operation, operational modes of the thermostat and the like. The most important information in thermostat displays is capable of being formed from segmented alphanumeric characters on less expensive LCDs without dot matrix capability and with reduced requirements for memory and programming.
Thus, dot matrix LCDs have not been widely used in prior art user programmable thermostats through a failure to understand an extended functionality capability of those devices when dot matrix LCDs are employed with a touch pad to effect an interactive display. This extended functionality is exploited to advantage in the present invention both to greatly simplify user programming and to relieve the manufacturer of the necessity to fabricate variants of the thermostat to suit the control and display aspects of various heating and/or cooling environments.
While the present invention may be practiced using segmented LCDs, it is preferably embodied using dot matrix LCDs.